According to the Centers for Disease Control and Prevention, the rates of all of our top 10 killers have fallen or stabilized except for one, suicide. As shown in my video, Antioxidants & Depression, accumulating evidence indicates that free radicals may play important roles in the development of various neuropsychiatric disorders including major depression, a common cause of suicide.

In a study of nearly 300,000 Canadians, for example, greater fruit and vegetable consumption was associated with lower odds of depression, psychological distress, self-reported mood and anxiety disorders and poor perceived mental health. They conclude that since a healthy diet comprised of a high intake of fruits and vegetables is rich in anti-oxidants, it may consequently dampen the detrimental effects of oxidative stress on mental health.

But that study was based on asking how many fruits and veggies people ate. Maybe people were just telling the researchers what they thought they wanted to hear. What if you actually measure the levels of carotenoid phytonutrients in people's bloodstreams? The same relationship is found. Testing nearly 2000 people across the United States, researchers found that a higher total blood carotenoid level was indeed associated with a lower likelihood of elevated depressive symptoms, and there appeared to be a dose-response relationship, meaning the higher the levels, the better people felt.

Lycopene, the red pigment predominantly found in tomatoes (but also present in watermelon, pink grapefruit, guava and papaya) is the most powerful carotenoid antioxidant. In a test tube, it's about 100 times more effective at quenching free radicals than a more familiar antioxidant like vitamin E.

Do people who eat more tomatoes have less depression, then? Apparently so. A study of about a thousand older men and women found that those who ate the most tomato products had only about half the odds of depression. The researchers conclude that a tomato-rich diet may have a beneficial effect on the prevention of depressive symptoms.

Higher consumption of fruits and vegetables has been found to lead to a lower risk of developing depression, but if it's the antioxidants can't we just take an antioxidant pill? No.

Only food sources of antioxidants were protectively associated with depression. Not antioxidants from dietary supplements. Although plant foods and food-derived phytochemicals have been associated with health benefits, antioxidants from dietary supplements appear to be less beneficial and may, in fact, be detrimental to health. This may indicate that the form and delivery of the antioxidants are important. Alternatively, the observed associations may be due not to antioxidants but rather to other dietary factors, such as folate, that also occur in plant-rich diets.

In a study of thousands of middle-aged office workers, eating lots of processed food was found to be a risk factor for at least mild to moderate depression five years later, whereas a whole food pattern was found to be protective. Yes, it could be because of the high content of antioxidants in fruits and vegetables but could also be the folate in greens and beans, as some studies have suggested an increased risk of depression in folks who may not have been eating enough.

Low folate levels in the blood are associated with depression, but since most of the early studies were cross-sectional, meaning a snapshot in time, we didn't know if the low folate led to depression or the depression led to low folate. Maybe when you have the blues you don't want to eat the greens.

But since then a number of cohort studies were published, following people over time. They show that a low dietary intake of folate may indeed be a risk factor for severe depression, as much as a threefold higher risk. Note this is for dietary folate intake, not folic acid supplements; those with higher levels were actually eating healthy foods. If you give people folic acid pills they don't seem to work. This may be because folate is found in dark green leafy vegetables like spinach, whereas folic acid is the oxidized synthetic compound used in food fortification and dietary supplements because it's more shelf-stable. It may have different effects on the body as I previously explored in Can Folic Acid Be Harmful?

These kinds of findings point to the importance of antioxidant food sources rather than dietary supplements. But there was an interesting study giving people high dose vitamin C. In contrast to the placebo group, those given vitamin C experienced a decrease in depression scores and also greater FSI. What is FSI? Frequency of Sexual Intercourse.

Evidently, high dose vitamin C improves mood and intercourse frequency, but only in sexual partners that don't live with one another. In the placebo group, those not living together had sex about once a week, and those living together a little higher, once every five days, with no big change on vitamin C. But for those not living together, on vitamin C? Every other day! The differential effect for non-cohabitants suggests that the mechanism is not a peripheral one, meaning outside the brain, but a central one--some psychological change which motivates the person to venture forth to have intercourse. The mild antidepressant effect they found was unrelated to cohabitation or frequency, so it does not appear that the depression scores improved just because of the improved FSI.

According to the Centers for Disease Control and Prevention, the rates of all of our top 10 killers have fallen or stabilized except for one, suicide. As shown in my video, Antioxidants & Depression, accumulating evidence indicates that free radicals may play important roles in the development of various neuropsychiatric disorders including major depression, a common cause of suicide.

In a study of nearly 300,000 Canadians, for example, greater fruit and vegetable consumption was associated with lower odds of depression, psychological distress, self-reported mood and anxiety disorders and poor perceived mental health. They conclude that since a healthy diet comprised of a high intake of fruits and vegetables is rich in anti-oxidants, it may consequently dampen the detrimental effects of oxidative stress on mental health.

But that study was based on asking how many fruits and veggies people ate. Maybe people were just telling the researchers what they thought they wanted to hear. What if you actually measure the levels of carotenoid phytonutrients in people's bloodstreams? The same relationship is found. Testing nearly 2000 people across the United States, researchers found that a higher total blood carotenoid level was indeed associated with a lower likelihood of elevated depressive symptoms, and there appeared to be a dose-response relationship, meaning the higher the levels, the better people felt.

Lycopene, the red pigment predominantly found in tomatoes (but also present in watermelon, pink grapefruit, guava and papaya) is the most powerful carotenoid antioxidant. In a test tube, it's about 100 times more effective at quenching free radicals than a more familiar antioxidant like vitamin E.

Do people who eat more tomatoes have less depression, then? Apparently so. A study of about a thousand older men and women found that those who ate the most tomato products had only about half the odds of depression. The researchers conclude that a tomato-rich diet may have a beneficial effect on the prevention of depressive symptoms.

Higher consumption of fruits and vegetables has been found to lead to a lower risk of developing depression, but if it's the antioxidants can't we just take an antioxidant pill? No.

Only food sources of antioxidants were protectively associated with depression. Not antioxidants from dietary supplements. Although plant foods and food-derived phytochemicals have been associated with health benefits, antioxidants from dietary supplements appear to be less beneficial and may, in fact, be detrimental to health. This may indicate that the form and delivery of the antioxidants are important. Alternatively, the observed associations may be due not to antioxidants but rather to other dietary factors, such as folate, that also occur in plant-rich diets.

In a study of thousands of middle-aged office workers, eating lots of processed food was found to be a risk factor for at least mild to moderate depression five years later, whereas a whole food pattern was found to be protective. Yes, it could be because of the high content of antioxidants in fruits and vegetables but could also be the folate in greens and beans, as some studies have suggested an increased risk of depression in folks who may not have been eating enough.

Low folate levels in the blood are associated with depression, but since most of the early studies were cross-sectional, meaning a snapshot in time, we didn't know if the low folate led to depression or the depression led to low folate. Maybe when you have the blues you don't want to eat the greens.

But since then a number of cohort studies were published, following people over time. They show that a low dietary intake of folate may indeed be a risk factor for severe depression, as much as a threefold higher risk. Note this is for dietary folate intake, not folic acid supplements; those with higher levels were actually eating healthy foods. If you give people folic acid pills they don't seem to work. This may be because folate is found in dark green leafy vegetables like spinach, whereas folic acid is the oxidized synthetic compound used in food fortification and dietary supplements because it's more shelf-stable. It may have different effects on the body as I previously explored in Can Folic Acid Be Harmful?

These kinds of findings point to the importance of antioxidant food sources rather than dietary supplements. But there was an interesting study giving people high dose vitamin C. In contrast to the placebo group, those given vitamin C experienced a decrease in depression scores and also greater FSI. What is FSI? Frequency of Sexual Intercourse.

Evidently, high dose vitamin C improves mood and intercourse frequency, but only in sexual partners that don't live with one another. In the placebo group, those not living together had sex about once a week, and those living together a little higher, once every five days, with no big change on vitamin C. But for those not living together, on vitamin C? Every other day! The differential effect for non-cohabitants suggests that the mechanism is not a peripheral one, meaning outside the brain, but a central one--some psychological change which motivates the person to venture forth to have intercourse. The mild antidepressant effect they found was unrelated to cohabitation or frequency, so it does not appear that the depression scores improved just because of the improved FSI.

In my video Preventing Asthma With Fruits and Vegetables, I highlighted an international study of asthma and allergies involving more than a million kids. The study found a consistent inverse relationship between prevalence rates of asthma, allergies, and eczema and the intake of plants, starch, grains, and vegetables. Researchers speculated "over a decade ago that if these findings could be generalized, and if the average daily consumption of these foods increased, an important decrease in symptom prevalence could be achieved." No need to speculate any more, though, because plants were finally put to the test.

Researchers have proposed that "by eating fewer fruits and vegetables, the susceptibility to potentially harmful inhaled substances of the population as a whole may be increased because of the reduction in antioxidant defenses of the lungs." The thin lining of fluid that forms the interface between our respiratory tract and the external environment is our first line of defense against oxidative damage. Oxidative damage is important in asthma, contributing to airway contraction, excessive mucous production, and hypersensitivity. Antioxidants protect against oxidative stress, so our lung lining contains a range of antioxidants our body makes itself, as well as those obtained from our diet, particularly from fruits and vegetables.

We can even quantify the level of oxidative stress in people by measuring the level of oxidation products in their exhaled breath, which drops as we start eating more fruits and vegetables, and drops further as we combine more plants with fewer animal foods.

Do those with asthma really have lower levels of antioxidants than people without asthma? Compared to healthy controls, subjects with asthma had lower whole blood levels of total carotenoids and lower levels of each of the individual phytonutrients they measured: cryptoxanthin, lycopene, lutein, alpha-carotene and beta-carotene compared to healthy controls.

Therefore, they posit, "the accumulating evidence does suggest that diet has an influence in modulating the response of the lung to inhaled allergens and irritants. However, it is possible that the reduced carotenoid levels in asthma are a result of increased utilization in the presence of excess free radicals." So it's like a chicken-or-the-egg phenomenon.

We know antioxidant-rich diets have been associated with reduced asthma prevalence. However, direct evidence that altering intake of antioxidant-rich foods actually affects asthma was lacking, until now.

There are two ways to test the effects of fruits and vegetables on asthma. Add fruits and vegetables to people's diets and see if their asthma improves, or take asthmatics and remove fruits and vegetables from their diets and see if they get worse.

The first such study of its kind, highlighted in my video, Treating Asthma With Fruits and Vegetables, placed subjects with asthma on a low antioxidant diet. After just a matter of days, there was a significant worsening of lung function and asthma control. The researchers conclude that "This finding is highly significant for subjects with asthma, as it indicates that omitting antioxidant-rich foods from the diet, for even a short time frame, will have a detrimental effect on asthma symptoms."

Ironically, the low antioxidant diet consumed by subjects, where they were restricted to one serving of fruit and up to two servings of vegetables per day, is typical of Western diets. In other words, the low antioxidant diet they used to worsen people's asthma, crippling their lung function, was just like the standard American diet.

As about "half the population usually consumes a diet with an intake of fruit and vegetables equivalent to that in the study diet or less, it appears likely that this dietary pattern, which must be considered suboptimal for lung health, may have a significant impact on asthma management, indicating the potential for typical Western dietary patterns to contribute to a worsening of lung function and asthma control."

Within just days, cutting down fruit and vegetable intake can impair lung function, but does adding fruits and vegetables help with asthma? That was the second phase of the study.

Asthmatics on the standard American diet had about a 40% chance of relapsing into an asthma exacerbation within three months. However, put them on seven servings of fruits and vegetables a day instead of three, and we cut their exacerbation rate in half, down to 20%. Imagine if there were a drug that could work as powerfully as a few fruits and vegetables.

If manipulating antioxidant intake by increasing fruit and vegetable intake can so powerfully reduce asthma exacerbation rates, why not just take antioxidant pills instead? I cover that in my video Treating Asthma With Plants vs. Supplements?

Cervical cancer is now considered a sexually transmitted disease. It was originally suspected as such, but now we have DNA fingerprinting proof that virtually all cervical cancer is caused by a sexually transmitted virus, human papilloma virus, which also causes cancers of the penis, vagina, vulva and throat. HPV is considered a necessary, but not sufficient cause of cancer.

I profile a study in my four minute video, Why Might Vegetarians Have Less HPV?, that shows that while most young women contract HPV, most don’t get cervical cancer because their immune systems are able to clear out the virus. Within one year, 70 percent of women clear the infection, and more than 90 percent clear it within two years — before the virus can cause cancer.

Might those with particularly strong immune systems clear the virus even faster? That’s what may be behind a new study that found vegetarian women had significantly lower infection rates with HPV, one of many studies reporting lower risk of HPV infection among those eating plant-based diets.

When researchers took a bunch of women with cancer-causing strains of HPV infecting their cervix and followed them out and retested at three months and nine months while analyzing their diets, what did they find? Higher levels of vegetable consumption appeared to cut their risk of HPV persistence in half, doubling one’s likelihood of clearing this potentially cancer-causing infection. And “higher” levels just meant about two or more servings a day. Antioxidants appear to suppress the activation of critical segments of the virus’ DNA. Maybe that’s why smearing green tea on genital warts—also caused by HPV—has been found so effective in clearing them (See my video, Treating Genital Warts with Green Tea).

In terms of preventing cervical cancer, phytonutrients like lutein (found in dark green leafy vegetables) and lycopene (the red pigment in tomatoes) may decrease viral load, thereby decreasing persistence and progression to disease. Bottom line: higher consumption of vegetables may decrease the risk of HPV persistence, which may help explain why a 2013 study found vegan women have significantly lower rates of all female cancers combined, including cancer of the cervix.